US Department of Labor
Bureau of Labor Statistics: How the Government Measures Unemployment
A detailed publication that explains how the government decides who is counted as unemployed and how they measure unemployment.
US Department of Labor
Bureau of Labor Statistics: Occupational Employment Statistics
Compares occupations in terms of numbers employed, projected employment growth, earnings, education and training requirements, opportunities for self-employment and part-time work, and unemployment rate.
Other
Historical Unemployment Data by Month (1948 2006)
United States unemployment figures for every month from January 1948 to December 2011.